Looks like machining/threading chips/debris, I would be very disappointed if I had built this engine.
The Vane/Rotor/Slide style oil pump can at least pass larger pieces without damage.....Gerotor & Gear pumps not so much.
GM is full of crap with these dates....They didn't want to issue a stop sale on 2025 models.
And if they aren't out & out lying with the dates....They were knowingly producing engines with poorly machined crankshafts for 2024 models! I know for a fact this defect affected 2019 & 2020 L87 pick-up trucks. (SUV's didn't get the L87 'till 2021).